Electrical resistance fusible link for a sprinkler head

ABSTRACT

The high temperature fusible connecting link maintaining a sprinkler head in closed position is replaced by a link formed by one or more strands of wire fusible by electrical resistance.

United States Patent [1 1 111-] 3,863,72 Young Feb. 4, 1975 ELECTRICAL RESISTANCE FUSIBLE LINK 56] References Cited FOR A SPRINKLER HEAD UNITED STATES PATENTS [76] Inventor: Richard J. Young, 2 1 3l S. V V. 4 2, 3,726,344 4/1973 Rothman et al. 169/37 Oklahoma City, Okla. 73119 Primary Examiner-Ll0yd L. King [22] Filed 1974 Assistant Examiner-Michael Mar [2]] Appl. No.: 450,951 Attorney, Agent, or FirmR0bert K. Rhea [52] U.S. Cl 169/59, 137/73, 169/61, [57] A R 4 169/40 Tl 1e high ternperature fusible connect ng link ma1n- [51] Int Cl Afizc 37/18 taming a sprinkler head in closed position IS replaced [58] Field o f S e a i' c li t d 975 835 60 61 37 by a formed by mm Strands of wire fusi' ble by electrical resistance.

4 Claims, 6 Drawing Figures III 'PATENTED EB 4mm FIG. 2

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FIG. 5

ELECTRICAL RESISTANCE'FUSIBIJE LINK FOR A SPRINKLER IIEA-D BACKGROUND OF THE INVENTION FIELD OF THE INVENTION The present invention relates to fire detecting systems and more particularly to an electrical resistance fusible link for sprinkler heads.

Conventional fire protection systems installed in department stores, office buildings, and the like, employ a sprinkler system including sprinkler heads arranged in selected spaced-apart relation with each sprinkler head maintained in a closed position by a fusible link. This link is normally fused by ambient heat, therefore, when a fire occurs it must burn and increase in intensity to a degree which will melt or fuse the link or links of sprinkler heads. Since these fusible links are made of low melting point metallic material, it seems obvious that the necessary heat to achieve the fusing action is a result of considerable flame having been generated. It seems obvious that if one or more sprinkler heads can be actuated or released in the area where the fire begins, assuming that the fire is not caused by a chemical explosion, then the release of a single sprinkler head would snuff out a fire in its initial stage or stages. This controlling of a fire or fires in their initial stages would not only conserve considerable merchandise but would result in less smoke and water damage being done as normally occurs when conventional sprinkler systems are activated as a result of a fire.

SUMMARY OF THE INVENTION The conventional ambient heat fusible link ofa sprinkler head is replaced by a length of electrical resistance fusible wire extending between and connected with the lever arm and strut maintaining a sprinkler head valve or cap in closed position. The electrically fusible wire is connected with a source of electrical energy through a detector head of a selected type. Electrical potential applied to the fusible wire in response to a signal from the detector head releases the sprinkler head lever arms and its cap.

The principle object of this invention is to provide an electrically fusible link for a sprinkler head which is fused to open at least one sprinkler head in response to an alarm signal thereby permitting water supply lines of smaller diameter and a reduction in water pressure.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a front elevational view of a sprinkler head connected with a fragment of a water supply line;

FIG. 2 is a vertical cross sectional view taken substantially along the line 2-2 of FIG. 1;

FIG. 3 is a bottom view of the fusible link looking in the direction of the arrows 3-3 of FIG. 2;

FIG. 4 is a horizontal cross sectional view of the fusible link taken substantially along the line 44 of FIG. 3;

FIG. 5 is a fragmentary perspective view illustrating an alternative form of the fusible link connected with another type sprinkler head; and,

FIG. 6 is a wiring diagram.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Like characters of reference designate like parts in those figures of the drawings in which they occur.

In the drawings:

The reference numeral l0 indicates one type of conventional sprinkler head used in fire protection systems. The sprinkler head 10 includes a valve body 12 threadedly connected with a tee l4 interposed in selected locations within a fluid conducting line 16. The valve body is provided with an orifice l8 normally closed by a valve or cap 20 held in place by lever arms, indicated generally at 22. The lever arms 22 comprise brace members 24, secured to the valve body at one end and connected with a fluid dispersing flange 26 at their other end. A release lever 28, substantially L- shaped inside elevation (FIG. 2), has the free end portion of its foot portion 30 contacting the juncture of the arcuate arms 24 and its leg portion 32 projecting toward the valve body 12 in spaced relation with respect to the arcuate arms 24. A strut 34 bears against the cap 20, at one end, and against the foot portion 30 of the L-shaped lever, at the other end, in off-set relation with respect to the axis of the orifice 18 so that movement of the lever leg portion 32 away from the strut permits fluid pressure contained by the line 16 to unseat the cap 20 and discharge water against the flange 26 which in turn forms a downwardly directed spray of the fluid from line 16. The above description is conventional with this type of sprinkler head and is set forth to show the operability of the instant invention.

The electrically fusible link is indicated generally at 40 and comprises a plate portion 42 and a fusible wire 44. The plate 42 is substantially U-shaped in plan view (FIG. 3) and surrounds an intermediate portion of the strut 34 which is normally disposed adjacent the bight portion 36 of the plate. A retaining plate 46 spans and contiguously contacts the leg portions 48 of the U- shaped plate. The retainer plate 46 is preferably connected with the plate legs 48 by soldering, for the purposes presently explained, and both the U-shaped plate legs 48 and retainer plate 46 may be dimpled, as indicated at 49, to insure a rigid connection.

In carrying out the invention, the L-shaped lever 28 is preferably provided with a cross bar 50 secured to the free end of its leg portion 32 to form a T-shape for this end portion of the leg of the L-shaped lever, as shown in FIG. 1. The wire 44 is preferably nichrome wire of 34 gauge and is secured at one end, as by soldering, as at 52, to the lever cross bar 50 and strung in a weaving action around and between a plurality of prongs or pins 54 secured, in cooperating spaced relation, to the cross bar 50 and adjacent end portion of the U-shaped plate 42. The other end portion of the nichrome wire is extended through an aperture 56 formed in the plate 42 and is secured therein by a ball or lump of solder 58 diametrically greater than the diameter of the opening 56. The pins 54 are electrically insulated from the lever cross bar 50 and plate 42 in any well known conventional manner, such as electrical insulating pads 57.bonded to the cross bar 50 and plate 42. Alternatively the lever 28 and strut 34 may be formed from dielectric material. The nichrome wire is in turn secured at its juncture with the solder lump or restriction 58 to one end of a wire 60 forming an electrical circuit 62. The electrical circuit 62 comprises a source of electrical energy, such as a 12 volt battery B, or the like. connected in series with the wire 60 through a switch S. The switch S forms a part of or is closed by a fire detecting signal head H which maybe one of any conventional type of smoke or firedetector.

Referring more particularly to FIG. 5, a fragment of another type sprinkler vhead is illustrated which employes a pair of arms 70 and 72 normally biased away from each other at one end by their other ends being juxtaposed in off-center frictional engagement between an orifice closing valve or cap 74 and a dispensing flange 76. in this embodiment the U-shaped plate 42 is similarly connected with the free end portion of the arm 72 and a substantially identical opposite plate 42 engages the free end of the other arm 70 with both plates 42 and 42' being provided with a plurality of the pins 54 for similarly receiving a winding of the nichrome wire 44 similarly connected with the circuit wire 60.

OPERATION 34 gauge nichrome wire has a resistance of 17.0 ohms per foot. The wire 44 comprises 2 /2 inches of such wire having a resistance of 3.57 ohms. Applying Ohms Law 3.36 amps. will be required at 12 volts or 40.34 watts to fuse the wire quickly. The tensil strength of the wire 44 is 8.67 pounds which is multiplied by the manner in which the wire 44 is laced or wound between the pins 54. In the event of fire or smoke detection, the detector head H closes the switch completing a circuit to ground through the wire 44 which fuses, releasing the levers 22 of FIG. 1 or the levers 70 and 72 of FIG. 5, thus actuating the respective sprinkler head. The purpose of the sandwiched solder juncture of the plates 42 and 46 is to insure that the solder joining these plates will be melted by ambient heat in the event of a malfunction of either the detector head H or circuit connected with the wire 44.

Obviously the invention is susceptible to changes or alterartions without defeating its practicability, therefore, I do not wish to be confined to the preferred embodiment shown in the drawings and described herein.

I claim:

I. An electrically actuated release for an individual sprinkler head having a body including a cap normally closing an orifice axially aligned with a water deflector and having lever means interposed between the cap and water deflector with at least one portion of the lever means being separable from another portion to release the cap, the improvement comprising:

lever connecting means including an electrically fusible strand normally preventing separating movement between said lever means; and,

an electrical circuit including a normally open switch connecting a source of electrical energy to ground through said strand.

2. The combination according to claim I and further including:

a detector head connected with said circuit for clos-,

ing said switch in response to a predetermined condition.

3. The combination according to claim 2 in which said lever connecting means includes:

plate means connected with said separable portion of said lever means; and,

at least one pin secured to each said plate means in dielectric relation, said strand extending between said pins in wraparound relation.

4. The combination according to claim 3 in which at least one of said plate means includes:

a U-shaped plate including leg portions surrounding an intermediate portion of said separable portion of said lever means in straddling relation: and.

a retainer plate extending between and soldered to said plate leg portions in superposed relation. l= =l 

1. An electrically actuated release for an individual sprinkler head having a body including a cap normally closing an orifice axially aligned with a water deflector and having lever means interposed between the cap and water deflector with at least one portion of the lever means being separable from another portion to release the cap, the improvement comprising: lever connecting means including an electrically fusible strand normally preventing separating movement between said lever means; and, an electrical circuit including a normally open switch connecting a source of electrical energy to ground through said strand.
 2. The combination according to claim 1 and further including: a detector head connected with said circuit for closing said switch in response to a predetermined condition.
 3. The combination according to claim 2 in which said lever connecting means includes: plate means connected with said separable portion of said lever means; and, at least one pin secured to each said plate means in dielectric relation, said strand extending between said pins in wraparound relation.
 4. The combination according to claim 3 in which at least one of said plate means includes: a U-shaped plate including leg portions surrounding an intermediate portion of said separable portion of said lever means in straddling relation; and, a retainer plate extending between and soldered to said plate leg portions in superposed relation. 